Lower extremity enhancer

ABSTRACT

A lower extremity enhancer to be worn by a user includes two leg supports having a plurality of jointed links. Proximal ends of the leg supports are connected to a back frame. Distal ends of the leg supports are connected to two foot links. The leg supports are powered by a plurality of actuators adapted to apply torques to the leg supports in response to movement of the user&#39;s legs.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.10/976,652, filed Oct. 29, 2004, which claims the benefit of U.S.Provisional Application No. 60/515,572, titled LOWER EXTREMITY ENHANCER,filed Oct. 29, 2003, the entire contents of which are incorporatedherein by reference for all purposes.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was made with government support under Contract No.DAAD19-01-1-0509 awarded by Defense Advanced Research Projects Agency(DARPA). The government has certain rights in the invention.

BACKGROUND

1. Field

The present application relates to a robotic exoskeleton, and, moreparticularly, to a lower extremity enhancer to be worn by a user toenable the user to carry a load.

2. Related Art

A robotic exoskeleton to be worn by a user has been mostly the subjectof science fiction. Attempts have been made to build a lower limbexoskeleton for both performance augmentation and rehabilitationpurposes. In general, these attempts relied on an interpretation ofmuscle activity to prescribe a motion to the joints of the exoskeleton,or on a conscious command signal from the user, or were limited to afixed set of predetermined physical activities. In general, the user ofthese exoskeletons was required to hold onto a walking aid when usingthe exoskeletons.

SUMMARY

In one exemplary embodiment, a lower extremity enhancer to be worn by auser includes two leg supports having a plurality of jointed links.Proximal ends of the leg supports are connected to a back frame. Distalends of the leg supports are connected to two foot links. The legssupports are powered by a plurality of actuators adapted to applytorques to the leg supports in response to movement of the user's legs.

DESCRIPTION OF DRAWING FIGURES

The present application can be best understood by reference to thefollowing description taken in conjunction with the accompanying drawingfigures, in which like parts may be referred to by like numerals:

FIG. 1 is a schematic view of an exemplary lower extremity enhancer;

FIG. 2 is a schematic perspective view of a single leg support;

FIG. 3 is a perspective view of a lower extremity enhancer showing thedegrees of freedom of some of the jointed links;

FIG. 4A is an exploded view of a jointed link;

FIGS. 4B and 4C are perspective views of the jointed link of FIG. 4A;

FIG. 5A is a schematic drawing of a jointed link for a knee region;

FIG. 5B is a section through the rotary joint (along the A-A plane) ofFIG. 5A;

FIG. 6 is an exploded view of a hydraulic actuator;

FIG. 7 is a schematic view of a back frame;

FIGS. 8A and 8B show a front and a back view of a detachable harness;

FIG. 9 is a schematic view of a hip assembly;

FIG. 10 is a schematic view of a hip assembly including jointed linksfor rotation and flexion/extension;

FIG. 11 is a schematic view of another hip assembly;

FIG. 12A is a schematic view of the side of a thigh link;

FIG. 12B is a schematic perspective view of a thigh link;

FIG. 13 is a schematic illustration of the side of a shank link;

FIG. 14 is an exploded view of a shank and thigh adjustment mechanism;

FIG. 15 illustrates a compliant shank attachment;

FIG. 16 is a schematic perspective view of a foot link;

FIG. 17 is a schematic illustration of the sole of a foot link;

FIG. 18 is an exploded perspective view of a foot link; and

FIG. 19 is a block diagram of an exemplary control system.

DETAILED DESCRIPTION

The following description sets forth numerous specific configurations,parameters, and the like. It should be recognized, however, that suchdescription is not intended as a limitation on the scope of the presentinvention, but is instead provided as a description of exemplaryembodiments.

1. Overview

With reference to FIG. 1, in one exemplary embodiment, a lower extremityenhancer (hereinafter referred to as an “enhancer”) 110 is adapted to beworn by a user to enable the user to carry a load. In the presentexemplary embodiment, enhancer 110 includes two leg supports 120, 130(right leg support 120 and left leg support 130) having multiple jointedlinks 122, 124, 132, and 134. A back frame 154, which carries the load,is connected to proximal ends of leg supports 120, 130. Two foot links162 are connected to distal ends of leg supports 120, 130. Actuators 166are adapted to apply torque to leg supports 120, 130.

Enhancer 110 includes multiple articulating joints that allow themovement of a user's lower extremities to be closely followed. In thepresent exemplary embodiment, right leg support 120 includes thigh link122 and shank link 124 rotatably jointed and configured to move inflexion and extension at a knee joint 146. Left leg support 130 includesthigh link 132 and shank link 134 rotatably jointed and configured tomove in flexion and extension at knee joint 146.

Foot links 162 and shank links 124, 134 are rotatably jointed andconfigured to move in flexion and extension at ankle joints 148. Footlinks 162 can be rigidly and releasably attached to a user's feet. Theregions of foot links 162 that contact the user's feet may includereleasable bindings or fasteners 160 to connect to the user's feet orshoes. Other methods of attachment to the user's feet are alsocontemplated, including direct attachment (for example, by wearing apair of “shoes” incorporated as part of enhancer 110), straps orbuckles, and the like.

Back frame 154 and thigh links 122, 132 are rotatably jointed andconfigured to move in flexion and extension at hip joints 144. Backframe 154 and thigh links 122, 132 are also rotatably jointed andconfigured to move in abduction and adduction at hip joints 140. Backframe 154 and thigh lines 122, 132 are rotatably jointed and configuredto move in rotation at hip joints 142. In FIG. 1, hip joints 142 areconnected to a hip assembly 152, which is shown connected to back frame154. It should be recognized, however, that hip assembly 152 can beintegral to back frame 154.

Back frame 154 can include connections to a load, or to other componentsof enhancer 110, such as a power supply or control system. The user isalso preferably attached to at least a portion of back frame 154. Thisattachment may be direct (e.g., strapping the user directly to backframe 154) or indirect (e.g., incorporating a detachable harness worn bythe user, which engages back frame 154). For ease of use, both the footattachments and the back attachments may be readily released by theuser.

Enhancer 110 is adjustable to fit a wide variety of user body shapes andsizes. Quick adjustments may be made to shorten or extend the length ofthigh links 122, 132, the length of shank links 124, 134, and the widthof hip assembly 152 (waist). Further, the fixed attachment sites at thefoot and back may also be adjusted to fit a variety of users.Alternatively, enhancer 110 can be fabricated to the precise dimensionsof a particular user (or narrow class of users).

Enhancer 110 may also be designed to be easily disassembled for eitherstorage or transport. For example, leg supports 120, 130 may bedetachable.

FIG. 2 shows a side perspective of left leg support 130. As depicted inFIG. 2, foot link 162 connects to an ankle region at the distal end ofshank link 134. The ankle region shown has two articulated joints (anactuated flexion/extension ankle joint 148 and a passiveabduction/adduction ankle joint 150). The shank link 134 connects tothigh link 132 at knee joint 146 configured to move inflexion/extension. Thigh link 132 connects to hip assembly 152, whichincludes three joints (hip joint 142 configured to move in rotation, hipjoint 140 configured to move in abduction/adduction, and hip joint 144configured to move in flexion/extension).

In the present exemplary embodiment, the joints of enhancer 110correspond to joints of the user. As an example, FIG. 3 shows aschematic of enhancer 110 with seven degrees of freedom on each legsupport, labeled: hip flexion/extension, hip rotation, hipabduction/adduction, knee flexion/extension, ankle abduction/adduction,ankle flexion/extension, and toe flexion/extension. Each degree offreedom corresponds to a single joint. These seven degrees of freedomare a subset of the degrees of freedom possible in most human lowerextremities. Enhancer 110 can incorporate all of the degrees of freedompossible in a human lower extremity, or it may incorporate a subset ofthem. In particular, enhancer 110 can include the hip flexion/extension,the knee flexion/extension, and the ankle flexion/extension joints.Enhancer 110 embodied in FIG. 1 incorporates all seven of the degrees offreedom (and thus seven joints) illustrated in FIG. 3.

While enhancer 110 shown in FIGS. 1 to 3 closely corresponds to theanatomy of the human lower extremity region (for example, the degrees offreedom described for the joints of enhancer 110 roughly correlate tothe degrees of freedom of the human hip, knee, and ankle joints), thiscorrespondence is not a requirement. Thus, for example, a human hipjoint is a ball-and-socket joint in which the upper leg is moved inflexion/extension, rotation, and abduction/adduction by a single joint.Further, all of these joints have the same axis of rotation. As shown inFIGS. 1 to 3, thigh links 122, 132 move in these directions by usingthree joints connected in series (hip joints 140, 142, and 144).

With reference to FIG. 1, in the present exemplary embodiment, some orall of the joints may be actively controlled or powered by actuators166. Actuators 166 may be of any type that is capable of controllablymoving a joint, such as electric motors, hydraulic motors, pneumaticmotors, and the like. For example, FIG. 1 shows hydraulic actuatorsconnected to a subset of the joints. Actuators 166 may have a controlinput (e.g., an electrical control input) and a power inputcorresponding to the type of actuator used at a given joint. In the caseof hydraulic actuators, the power input is pressurized hydraulic fluid.

The exemplary embodiment of enhancer 110 illustrated in FIGS. 1 to 3 ispowered at only the hip flexion/extension, the knee flexion/extension,and the ankle flexion/extension joints. It is possible, and may bedesirable, to power additional degrees of freedom. On the other hand,reducing the number of powered joints (and therefore the number ofactuators) may also significantly reduce the weight and powerrequirements of enhancer 110.

In the present exemplary embodiment, sensors are used throughoutenhancer 110 for detecting the position or status of enhancer 110 andthe user. For example, sensors may detect: relative (or absolute)position of enhancer 110 and its components, the forces acting onenhancer 110 (particularly the joints), and the movement (e.g., velocityand acceleration) of the components. Sensors may be located anywhere onenhancer 110, particularly on and around the joints, actuators, links,and back frame. The sensors provide input into a control system,including a controller, which is configured to process the informationand control the actuators.

In the present exemplary embodiment, enhancer 110 follows the motions ofa user's lower extremities, shadowing the user's movements, and allowingthe user to carry a load attached to back frame 154 without using a handcontrol. A user attached to enhancer 110 at the feet and back may walk,run, squat, bend, sit, swing from side to side, twist, climb, andmaneuver on ascending and descending slopes.

Enhancer 110 may be worn and operated in both an “un-powered” and a“powered” state. When enhancer 110 is un-powered (meaning that theactuators are not actively actuating the joints), enhancer 110 passivelyfollows the motions of the user's legs. In one exemplary embodiment,un-powered enhancer 110 supports loads in the vertical direction, whilemotion in the horizontal direction is provided by the user. Thus, thedesign of enhancer 110 may incorporate a number of variations in orderto simplify use in the un-powered state. For example, the overall weightof enhancer 110 may be kept low by choosing low-weight materials, or byreducing the number of powered joints.

When enhancer 110 is “powered,” movements are assisted by actuators 166,and follow a user's leg motions. In the “powered” state, slight userfeedback on enhancer 110 causes actuators 166 to actuate the joints andassist with the motion. For example, a user walking while wearing apowered enhancer exerts torsion on enhancer 110, particularly at thejoints. This torsion is detected by sensors, and used to calculate theappropriate force to be applied (e.g., at a joint) to assist the motion.The force applied by actuators 166 effectively reduces the impedancefelt by the user wearing enhancer 110.

Thus, enhancer 110 tracks the motions of a user's lower extremities.Optimally in the powered state, the user only minimally feels enhancer110 and any load supported by enhancer 110. Further, enhancer 110 doesnot significantly inhibit a user's movements, allowing the user a fullrange of motion in both the powered and the un-powered state.

Enhancer 110 may incorporate a number of “safety” features to protectboth the user and enhancer 110. The range of motion of a particularjoint may be limited so that the user cannot exceed the safe operationalrange, or to protect the user by preventing enhancer 110 or the userfrom exceeding a range of motion, which might harm the user. Enhancer110 may include a balance control so that the user cannot unknowinglystep too far beyond the center of gravity of enhancer 110 and the load.Safety features such as these could be implemented by feedback at thejoints that increases the impedance of the joint as it approaches adangerous position. Absolute limits of joint movement could also bedetermined by the design of the joint.

2. Joints

As described above, enhancer 110 includes multiple links connected atjoints. In the present exemplary embodiment, two links can be connectedwith multiple joints. For example, shank links 124, 134 and foot links162 are connected with multiple ankle joints 148, 150, where ankle joint148 corresponds to a flexion/extension motion and ankle joint 150corresponds to an abduction/adduction motion. In FIGS. 1 to 3, hipassembly 152 is shown with three hip joints 140, 142, and 144,corresponding to the abduction/adduction, rotation, andflexion/extension directions of motion. Various types of joints may beused to achieve the desirable range of motion. Examples of typicaljoints include but are not limited to: rotary joints, flexible joints,spring joints, and the like.

An example of a rotary joint is shown in FIG. 4A for left leg support130 between thigh link 132 and shank link 134. The proximal end of shanklink 134 and the distal end of thigh link 132 are coupled together inknee joint 146, which is a rotary joint. A rotary joint allows rotationin a given axis and deflects very little under the forces or momentsabout the other axes.

FIG. 4A illustrates an exploded view of knee joint 146. Knee joint 146is assembled from the proximal region of shank link 134 and the distalregion of thigh link 132, two bearing plates 410, an actuator mount 440,two sets of bearings 412, an encoder 420, and fasteners 430. In thisexample, shank link 134 is fastened to a bearing plate 410, which housestwo bearings 412 that surround the distal end of thigh link 132.Bearings 412 movably contact the surface of the distal end of thigh link132. In FIG. 4A, two complement bearings 412 are spaced one inch apartto minimize friction. Although bearings 412 shown are ball bearings, anybearings capable of withstanding the forces acting on the joint (moment)could be used, including wide brush or journal bearings. Sensors, suchas encoders (rotational encoders), may be included in the joint design.The joint may include attachment site(s) for an actuator or actuators.In the present exemplary embodiment, knee joint 146 of right leg support120 (FIG. 1) is a minor image of knee joint 146 of left leg support 130(FIG. 1).

With reference to FIGS. 4B and 4C, knee joint 146 includes a mechanicalstop surface 460 that limits rotation between thigh link 132 and shanklink 134. The relative angle between thigh link 132 and shank link 134is limited because the surface of the distal end of thigh link 132 willcontact mechanical stop surface 460 on bearing plate 410. This limitsthe range of motion of knee joint 146 and can protect both knee joint146 and the user. The position of mechanical stop surface 460 (e.g., therange of motion of knee joint 146) can be changed, for example, byaltering the shape of bearing plate 410. Further, bearing plate 410 andsurrounding structure (e.g., thigh link 132 in the example above) may bedesigned to enhance stop performance. For example, when knee joint 146is bent to the extreme of its range of motion, bearing plate 410 andthigh link 132 can include parallel surfaces that contact each otherwith a large surface area. Also, a coating or protective layer (e.g.,neoprene rubber) could be added to mechanical stop surface 460 toprotect the surface and to reduce impact.

FIG. 5A is a schematic drawing of knee joint 146. A section through theknee joint 146 (along the A-A plane) is shown in FIG. 5B. Encoder 420 ismounted to thigh link 132 and held in position by an outer retainingring 510. Other sensors for detecting position, movement, and forcesacting on knee joint 146 could also be mounted at knee joint 146, thighlink 132, or shank link 134.

The materials chosen for the components of knee joint 146 should beappropriate for the functions of the joint. For example, the bearingplates should be made of a high-strength, low-weight material, such asAluminum (e.g., 7075 Aluminum). Stronger materials such as Titanium mayalso be used, or used for other components of knee joint 146, such asthe retaining rings for the bearings. These materials are offered asexamples only; in general, the components of enhancer 110 (FIG. 1) canbe made of any metal, alloy, polymer, ceramic, rubber, or other materialor combination of materials with adequate mechanical, electrical, andchemical properties.

With reference to FIG. 1, other rotary joints may include additionalcomponents, or may omit some of the components shown in FIG. 4A. Forexample, joints that are not actuated will not require actuator mounts.Joints with a single bearing set may also be used. In addition, theloads seen by each jointed link will influence the design requirementsof each joint. In general, joints that bear high forces (torsion,stress, strain) may include additional support or mechanical adaptationsto help withstand these forces.

The orientation of a joint depends on the intended direction of motionfor that joint. For example, the human knee moves in flexion andextension in the human's sagittal plane; thus knee joint 146 may also beconfigured to move in flexion and extension (in the user's sagittalplane). In another example, the human hip joint is capable of moving inrotation, flexion/extension, and abduction/adduction. Thus enhancer 110can include a plurality of joints in different configurations toapproximate these same movements. Although the joints described aboveare configured to move in only one plane (e.g., flexion/extension),other joint configurations could be used with enhancer 110. For example,joints configured to move in both rotation and flexion/extension, orjoints configured to move in rotation, flexion/extension, andabduction/adduction, could all be used with enhancer 110.

Joints may be connected to an actuator or not connected to an actuator.In one exemplary embodiment, only joints moving in the flexion andextension direction (in the sagittal plane of a user) are powered byactuators.

3. Actuator

As described above, in the “powered” state, the powered joints arecontrollably moved by actuators 166. Actuators 166 can include but arenot limited to: pressure-based actuators (e.g., hydraulic, pneumatic,etc.), electric actuators, thermal actuators, mechanical actuators, andhybrids and combinations of these. For the sake of simplicity, theexamples described herein are hydraulic actuators; however, any actuatoradaptable to apply force to a joint may be used, as will be apparent toone skilled in the art. Further, different kinds of actuators 166 may beused to apply force to different joints.

In one exemplary embodiment, linear hydraulic cylinders are used toactuate the ankle, knee, and hip joints. The forces applied at thesejoints may be relatively low for hydraulic actuators (a few hundredpounds), thus small-bore hydraulic cylinders with a supply pressure ofapproximately 1000 psi may be used. In one exemplary embodiment, thehydraulic actuator may have a long stroke length (e.g., 4-5 inches).Power for the hydraulic actuators could be supplied by hydraulic hosesconnected to a central hydraulic pressure source (power source). Thus,enhancer 110 may include any of the components required to power andoperate the hydraulic actuators. For example, servo-valves may be usedto regulate hydraulic flow in and out of each cylinder. When other typesof actuators are used, enhancer 110 may likewise be adapted toincorporate any of the components required.

The controller may be adapted to the different kinds of actuators usedin different embodiments of enhancer 110. The controller controls theactuators, and thus may be calibrated to accurately command an actuatorand coordinate its movement with the rest of enhancer 110 and the user.Thus, the controller may incorporate response parameters of eachactuator, such as time response, energy requirements, force output,impedance, and the like.

FIG. 6 is an exploded view of a hydraulic actuator 166. A cylinder body602 attaches to one region of a link (e.g., along the long axis of shanklink 124, 134 (FIG. 1)), and a rod end 604 connects to the actuatormount portion of a bearing plate. A cylinder rod 606 can move withincylinder body 602 when a controller regulates the hydraulic pressurewithin cylinder body 602. Additional components may also be included aspart of actuator 166, such as adaptors or sensor 168. In FIG. 6, forcesensor 168 is included at rod end 604 before attachment to the bearingplate. Force sensor 168 may provide information used by the controllerto detect forces (e.g., torques) acting at the joint.

4. Power Supply

With reference to FIG. 3, enhancer 110 may be powered by an on-boardpower source 302 or by an off-board power source. On-board powersupplies are typically carried by enhancer 110 (e.g., on back frame154). The power supply may be virtually any power source capable ofdriving the actuators. Thus, for hydraulic actuators, a power source mayinclude a pump and an accumulator for generating and storing hydraulicpressure. Other pressure-driven actuators may likewise use otherpump-based systems, including but not limited to: electric-motor drivenpumps, internal combustion-engine pumps, or chemically-driven pumps. Oneexample of a chemically-driven pump appropriate for enhancer 110 is amonopropellant-powered system in which H₂O₂ is catalytically reacted toproduce oxygen gas and water vapor. The actuator power supply may beseparate from power supplies running other components of enhancer 110(e.g., the controller), or even other actuators. In one exemplaryembodiment, the power supply is the same for all of the components ofenhancer 110. In one exemplary embodiment, enhancer 110 includes abackup power supply. In one exemplary embodiment, the power supply is abattery.

5. Back Frame

In one exemplary embodiment, some portion of back frame 154 rigidlyattaches to a user, either directly or though an intermediary, such as aharness. However, back frame 154 does not substantially interfere withthe user's lower extremities and is configured to bear a load.

Back frame 154 has an outer side (facing away from a user) and an innerside (adjacent to a user). With reference to FIG. 2, back frame 154 mayinclude sensors (for example, force sensors 174 to detect contact andforces between the user and enhancer 110, and inclinometer 208 to detectthe angle of enhancer 110 relative to the ground) on any part of backframe 154. Back frame 154 may also include attachment sites for thepower supply, additional equipment, a pack, or a load, preferably on theouter side of back frame 154. The inner side of back frame 154 mayinclude a mount to attach to a user, such as straps or buckles.

FIG. 7 shows a schematic example of the outer side of back frame 154.Back frame 154 has a housing 172 for the electronics (e.g., thecontroller and other electronics), mounted sensors (e.g., inclinometer208 and force sensor 174), and hydraulic tees 702 for connecting theactuators to a hydraulic power source. Back frame 154 also includesholes 704 for mounting additional components. The lower portion of backframe 154 may also be integrally configured as hip assembly 152 (FIG. 1)that attaches to leg supports 120, 130 (FIG. 1). Alternatively, hipassembly 152 (FIG. 1) may be separable from back frame 154, and attachto it.

A harness configured to be worn by a user may also be part of back frame154. The harness may be integral to back frame 154 or a detachable part.FIGS. 8A and 8B show an example of a detachable harness 802. FIG. 8Ashows the front of harness 802 being worn around a user's torso. Harness802 has straps that fit over a user's shoulders and around the user'swaist, and can be adjusted to fit users of different sizes. FIG. 8Bshows the back of harness 802 in FIG. 8A, which can removably attach toenhancer 110 (FIG. 1).

6. Hip Assembly

With reference to FIG. 1, as described above, the lower region of backframe 154 may be configured as hip assembly 152 for attachment to legsupports 120, 130. Alternatively, hip assembly 152 may be a separateregion that attaches to back frame 154 in a rigid fashion.

FIG. 9 shows a schematic view of one version of hip assembly 152. Hipassembly 152 includes connections between the links of the most proximalportions of leg supports 120, 130 (FIG. 1) and back frame 154 (FIG. 1).In FIG. 9, hip assembly 152 is also adjustable to allow users ofdifferent sizes to adjust enhancer 110 (FIG. 1) to fit their bodymorphology. The width of hip assembly 152 can be changed (correspondingto the user's girth), for example by swapping out a hip spacer 902 inthe region between two hip joints 140. In one exemplary embodiment, hipspacer 902 is a lockable slider that can be moved to adjust the distancebetween hip joints 140.

In FIG. 9, hip joints 140 are part of the jointed link encompassing backframe 154 (FIG. 1) and hip spacer 902. In one exemplary embodiment, ahip range of motion includes abduction/abduction, rotation, andflexion/extension. In one exemplary embodiment, this range of motion maybe achieved using three hip joints in series. FIG. 9 is one example ofthis range of motion, in which the hip assembly 152 includes a hip arc904 on the right and left sides. Hip arcs 904 serve as segments of thejointed links; in FIG. 9, hip arc 904 is part of hip joint 140.

FIG. 10 shows a hip assembly 152 including jointed links for rotationand flexion/extension. Alternative arrangements of the joints attachedat the hip are also possible.

FIG. 11 is an alternative design of hip assembly 152 showing that thejoints of enhancer 110 (FIG. 1) may be placed in any position thatpermits the user to move relatively unencumbered by the position ofenhancer 110 (FIG. 1).

7. Thigh Links

With reference to FIG. 1, as described above, the proximal end of thighlinks 122, 132 connect to hip assembly 152 or back frame 154. Theproximal ends of thigh links 122, 132 and hip assembly 152 form a joint,and the distal part of thigh links 122, 132 and shank links 124, 134form another joint. Overall, thigh links 122, 132 should be relativelyrigid (relatively inflexible), although they may be adjustable.

FIGS. 12A and 12B show one example of a thigh link 122, 132. In FIGS.12A and 12B, the main structure of thigh link 122, 132 includes an outerpiece 1202 and an inner piece 1204 that slide relative to each other forlength adjustment. Outer piece 1202 attaches to knee joint 146 (FIG. 1)and actuator 166 (FIG. 1). Inner piece 1204 connects with hip joint 144(FIG. 1) and actuator 166 (FIG. 1). Thus, thigh link 122, 132 may beadjusted to fit a variety of user sizes. FIGS. 12A and 12B also show aquick release mechanism for adjusting the length of thigh link 122, 132in which two handles 1206, 1208 can be locked down to hold the adjustedinner and outer pieces 1204, 1202 in position.

In one exemplary embodiment, the region of thigh link 122, 132 thatfaces the user is kept substantially clear of components, reducing thechances that enhancer 110 (FIG. 1) will contact the user's leg orinterfere with user mobility. In general, however, the other faces ofthigh links 122, 132 (e.g., the outer faces) may include mountings foradditional components such as sensors and controller components. InFIGS. 12A and 12B, a component is shown attached to the outer surface ofthigh link 122, 132. Thigh link 122, 132 can also include attachmentsfor power supply components (e.g., pneumatic, hydraulic, or electricallines) and actuators.

8. Shank Link

With reference to FIG. 1, the distal end of shank links 124, 134 andfoot link 162 form a joint at the ankle, and the proximal ends of shanklinks 124, 134 and the distal ends of thigh links 122, 132 form a jointat the knee. FIG. 13 shows an example of a shank link 124, 134. In FIG.13, shank link 124, 134 has two straight pieces that can slide relativeto each other, an outer shank 1302 and an inner shank 1304. Outer shank1302 connects to ankle joint 148 (FIG. 1). The position of the inner andouter shanks 1304, 1302 can be adjusted to change the overall shanklength based on the user's morphology, similar to the thigh adjustmentdescribed above. Also, the proximal and distal regions of shank link124, 134 may be adapted to facilitate forming a joint. For example, inFIG. 13, the proximal region of inner shank 1304 is adapted to form ajoint with thigh link 122, 132 (FIG. 1) by including a flattened, largersurface area for attachment to a rotary joint.

FIG. 14 illustrates one exemplary embodiment of a shank and thighadjustment mechanism. In FIG. 14, the link (shank link 124, 134 (FIG. 1)or thigh link 122, 132 (FIG. 1)) can be adjusted by quick-releaseclamps. Adjustment of shank links 124, 134 (FIG. 1) and thigh links 122,132 (FIG. 1) is important for both versatility and user comfort. Thequick-release mechanism shown is a simple method of adjustment. The linkis shown with an outer link 1402 that is a U-shaped channel piece thatslidably mates with an inner link 1404. Adjustment in the quick-releasesystem is done in discrete intervals (based on the spacing of adjustmentholes 1406). The link is locked into position by aligning the adjustmentholes of the inner and outer links 1404, 1402, then screwing a threadedrod into a clamping cone 1408 on one side of a hole and a threaded cone1410 on the opposite side. Pushing handles 1412 down then locks innerand outer links 1404, 1402 into position. Cones 1408 can be coated in(or fabricated from) a compressible material, such as rubber.

With reference to FIG. 1, shank link 124, 134 may also have additionalattachment sites for other components of enhancer 110 (e.g., sensors orcontrol system components). Shank link 124, 134 may also include acompliant attachment to connect to a user's lower leg to increasecontrol over leg supports 120, 130. An example of this is shown in FIG.15. Compliant attachment site 1502 may be adjustable, for example, by astrap or buckle system. In one exemplary embodiment, a compliant strap1504 is buckled to a shin guard 1506 worn by the user.

9. Foot Links

With reference to FIG. 1, as described above, enhancer 110 has an ankleregion formed by the joining of shank links 124, 134 and foot links 162.As also described above, foot links 162 rigidly attach to the user'sfeet. In addition, foot links 162 can include additional joints (e.g.,to allow flexing/extension of the toes), connections to secure theuser's feet, and sensors to detect contact with the ground, contact withthe user, motion, etc.

FIG. 16 is a schematic diagram of foot link 162, showing the side ofsole 1602, foot bindings 1604, ankle sections 1606, 1608, and toe region1610. With reference to FIG. 17, sole 1602 protects the components offoot link 162 while walking over rugged terrain, and may also housesensors. Sole 1602 is preferably molded from a durable and compliantmaterial, such as a polymer (polyurethane, etc.) or other elastomer(e.g., rubber, etc.). If sole 1602 is somewhat compliant, it will helpdampen unwanted impact spikes on the user and enhancer 110 (FIG. 1), aswell as assisting enhancer 110 (FIG. 1) and the user in moving overvaried terrain. Sole 1602 may also include a material, shape, or texturethat helps with surface traction.

A plurality of sensors may be embedded in or integral to sole 1602. InFIG. 17, five touch sensors are embedded at tip 1702, toe 1704, ball1706, middle 1708, and heel 1710. The touch sensors communicate with thecontrol system and provide information on how foot link 162 ispositioned on the ground. Sole 1602 may be formed of materials withdifferent densities to help ensure that the touch sensors are depressedwhen a region of foot link 162 is in contact with the ground. In oneexemplary embodiment, the area in sole 1602 around the touch sensors maybe made of a less compliant material (e.g., higher-density polymer) thanthe rest of sole 1602 (e.g., a lower-density polymer).

With reference to FIG. 18, foot link 162 may also incorporate one ormore accelerometers 1802. Accelerometers 1802 could be intrinsic to sole1602 or mounted onto foot link 162 in some other region. For example,accelerometer 1802 may be bolted directly to heel 1710, and protectedwithin a metal housing.

With reference to FIG. 17, sole 1602 is the most distal region ofenhancer 110 (FIG. 1), and it may lie beneath a structural frame thatsupports the rest of foot link 162. Heel 1710 is rigid, and may be madeof a rigid metal, such as aluminum. Heel 1710 forms a joint with toe1704 and ball 1706 of foot link 162. This joint may be a flexible jointmade, for example, of a compliant material, which allows slight bendingof this joint as enhancer 110 (FIG. 1) follows the motion of the user.Thus, sole 1602, ball 1706, and toe 1704 may be made of compliantmaterials. The entire toe 1704 and ball 1706 region of the foot link 162may be flexible.

Heel 1710 is also part of the ankle joint 148 (FIG. 1). With referenceto FIG. 1, in one exemplary embodiment, two joints connect foot links162 to shank links 124, 134: ankle joint 148 moves the ankle inflexion/extension, and ankle joint 150 moves the ankle inabduction/adduction. Ankle abduction/adduction may be accomplishedthrough a spring joint, as shown in FIG. 18. The spring element easesthe load on the user's ankles. In FIG. 18, the spring joint is shown asmultiple compliant plates 1804 attached to heel 1710. Compliant plates1804 may be made, for example, of steel or other appropriate springmaterial. Attached to the proximal end of the spring joint is a rotaryjoint for moving the ankle in flexion/extension. The ankle of enhancer110 (FIG. 1) may have either a flexion/extension joint or anabduction/adduction joint, or both. In FIGS. 16 and 18, both joints areshown and are connected in series, potentially allowing greaterflexibility.

As discussed above, the user is rigidly attached to foot links 162, andpreferably, the user's foot is releasably bound to foot links 162. Oneexemplary embodiment of a releasable binding 160 is shown in FIGS. 16and 18, and is modeled after a snowboard binding. For example, a Type-Nclick-in snowboard binding may be used. Ideally, the binding does notinterfere with the bottom of the boot/shoe, and can easily be affixed toa standard boot/shoe. Other types of bindings, including snaps, belts,straps, buckles, and the like, may also be used. In one exemplaryembodiment, the user's feet can be bound to foot links 162 without anadditional shoe component. In one exemplary embodiment, the user's feetcan be bound to foot links 162 without requiring the user to wearseparate shoes.

10. Sensors

With reference to FIG. 1, enhancer 110 includes sensors for providingkinematic and dynamic data about the status of enhancer 110. Sensors mayprovide information about the joint angles and velocities of the joints,the acceleration of different regions of enhancer 110, the absolute footangle of enhancer 110, the center of gravity of enhancer 110, and anyforces acting on the joints and links of enhancer 110. These sensors arepart of the control system (or systems) for enhancer 110. The controlsystem may use this data to control the actuators and move enhancer 110.

In one exemplary embodiment, torque applied to a joint is measured atthe joint by measuring the force at the actuator with force sensor 168.When the actuator is a hydraulic actuator, joint torque at the actuatedjoint may be measured by estimating the moment arm through the jointangle. Force sensor 168 may be included as part of the actuatormounting. In this arrangement force sensor 168 measures both the forceapplied by the actuator and the forces applied by the user and/or theenvironment on that joint. A rotary encoder may also be included as partof a link, to measure the relative angular position of the segments ofeach link. Preferably, a rotary encoder with a high resolution is used(e.g., approximately 40,000 counts/revolution). Such rotary encoders mayalso be used to measure absolute joint angle. Angular velocity may becalculated, as may acceleration of the joint.

In one exemplary embodiment, additional sensors directly measureparameters such as acceleration, avoiding excessive computation time,and increasing accuracy. For example, accelerometers may be includedthroughout enhancer 110, particularly at the joints and links. In oneexemplary embodiment, linear accelerometers are used to measureacceleration of different regions of enhancer 110. For example,acceleration of shank links 124, 134 is measured by multipleaccelerometers 202 (FIG. 2) mounted parallel to one another in the samesagittal plane of shank links 124, 134. Preferably, a pair ofaccelerometers is used to measure the acceleration of a region or bodysegment of enhancer 110. Angular acceleration (e.g., joint angularacceleration) can be obtained by measuring linear acceleration of twopoints a fixed distance apart on a region or body segment, such asaccelerometers 204, 206 (FIG. 2) on back frame 154. Alternatively, asingle rotary accelerometer may be used.

Sensors may also be used to detect the foot angle or foot contactbetween enhancer 110 and the ground. Contact sensors on the bottom offoot links 162 may be used to indicate the position of the foot withrespect to the ground, such as toe contact, heel contact, etc. Forcesensors may be used in place of, or in addition to, contact sensors tomeasure the ground forces acting on enhancer 110.

The position of the user or the torso of enhancer 110 with respect togravity can be measured using one or more inclinometers 208. Withreference to FIG. 7, in one exemplary embodiment, inclinometer 208 ismounted to back frame 154 to detect the angle of back frame 154. Thecontrol system may also use data from inclinometer 208 to detect jointangles from toe 1704 (FIG. 17), as well as the center of gravity ofenhancer 110 (FIG. 1).

With reference again to FIG. 1, sensors could also be included tomeasure forces between the user and enhancer 110. For example, amulti-axis force/torque sensor 174 may be mounted on back frame 154 tomeasure forces between the user and enhancer 110.

Additional sensors may be included to provide feedback between enhancer110 and the ground and/or the user. The control algorithms used by thecontrol system may further refine the number and types of sensors usedby enhancer 110. Enhancer 110 may also include sensors to detectparameters unrelated to force, position, velocity, and acceleration.Examples of other kinds of sensors which may be used in enhancer 110include but are not limited to: temperature sensors, power-leveldetectors, weighted-load detectors, etc.

11. Control System

With reference to FIG. 19, an exemplary control system 1900 is depicted.Exemplary control system 1900 includes remote or central Input/Outputmodules (RIOMs) 170, a supervisor I/O module (SIOM) 1902, and acontroller 1904.

RIOMs 170 collect analog and digital sensor signals at differentlocations on enhancer 110 (FIG. 1). In one exemplary embodiment, eachRIOM 170 includes three 14-bit±4V A/D converters, one encoder quadraturecounter, six TTL digital inputs, and one 16-bit±5V D/A converter.Additionally, in the exemplary embodiment depicted in FIG. 1, two RIOMs170 are disposed on each shank link 124, 134. One RIOM 170 is disposedon each thigh link 122, 132. Four RIOMs 170 are disposed on hip assembly152. It should be recognized, however, that any number of RIOMs 170 canbe disposed at various locations on enhancer 110.

With reference again to FIG. 19, RIOMs 170 are connected to SIOM 1902 intwo chain-like structures using 200 Mbps digital communication lines andpower supply lines. SIOM 1902 transmits data between RIOMs 170 andcontroller 1904, such as through a parallel I/O bus, a PCI board, and aPCI interface.

In one exemplary embodiment, controller 1904 is a single board computer(SBC), such as a Cool RoadRunner II PC/104-Plus SBC with a NationalSemiconductor Geod GX1 300 MHz processor. SIOM 1902 and controller 1904can be disposed within housing 172 (FIG. 1). It should be recognized,however, that controller 1904 can be a series of distributedcomputers/processors rather than an SBC.

In one exemplary embodiment, controller 1904 is capable of beingmodifiably “programmed” to output appropriate actuator responses basedon data received from the sensors. The controller is pre-programmed tooutput actuator responses based on sensor input data.

In one exemplary embodiment, controller 1904 implements a master controlalgorithm (the Supervisor task). The algorithm calculates requiredtorques to be applied at each powered joint, and issues command signalsto the controllable actuators, e.g., by sending a current to a hydraulicservo-valve corresponding to the force to be applied by the hydraulicactuator. The algorithm loop speed is determined by a counter (e.g., 2kHz counter) signal. Thus, the sampling rate for this version ofenhancer 110 (FIG. 1) is 2 kHz. Faster or slower sampling rates may alsobe used. Preferably, sampling rates are faster than 60 Hz (twice thefrequency content of normal walking) and more preferably faster than600-1200 Hz.

In one exemplary embodiment, in the powered mode, controller 1904, andin particular the master control algorithm running on controller 1904,ensures that enhancer 110 (FIG. 1) moves in concert with the user withminimal interaction forces between the user and enhancer 110 (FIG. 1).The algorithm ensures that the external forces on both the user andenhancer 110 (FIG. 1) are similar, but scaled appropriately to theirmasses. The algorithm ensures that the device-ground reaction forces areproportional to the user-ground reaction forces, and that the centers ofgravities of the user and enhancer 110 (FIG. 1) move together. Thealgorithm regulates the torque applied at the powered joints.

In particular, with reference to FIG. 1, the human gait cycle may bedivided into a stance phase (in which one or both leg supports 120, 130support the user's weight) and a swing phase (in which a leg is out ofcontact with the ground, preparing for the next step). These phases maybe further broken down into parts (e.g., heel strike, toe-off, etc.),during which the forces acting on the legs may be determined, includingthe forces acting on different regions of the legs. Enhancer 110 may usethe position of the user's legs to help determine enhancer motion. Thealgorithm running on controller 1904 (FIG. 19) may thus estimate theappropriate force to be applied at a region (or joint) of enhancer 110in order to allow a user to walk relatively unencumbered while carryinga load with enhancer 110.

The algorithm running on controller 1904 (FIG. 19) regulates actuators166, causing them to track a desired force. The algorithm determines theappropriate force to be applied at each actuator 166 by processing inputfrom sensors, and applying these measurements to control each actuator166. The algorithm coordinates all actuators 166 of the powered jointsso that actuator 166 moves without hindering the movements of the user.

With reference again to FIG. 19, in one exemplary embodiment, thealgorithm running on controller 1906 processes joint variables such asjoint angle, joint velocity, and joint force. The algorithm calculatesthe appropriate forces to be applied by the actuators knowing thesevariables. For example, a given actuator should apply force at a jointso that there is not a significant requirement for user-applied force inorder to move a link. Thus, the user is not significantly encumbered bythe impedance (or resistance) due to enhancer 110 (FIG. 1) as the usermoves. The more powered joints that enhancer 110 (FIG. 1) has, the lessthe user will be encumbered, although the computational time for thealgorithm may increase.

With reference to FIG. 1, in one exemplary embodiment, the algorithmrunning on controller 1904 (FIG. 19) processes forces applied by theuser's foot and the forces applied by the ground on foot links 162. Thealgorithm (FIG. 19) then calculates the forces applied at the jointsbased on the ground forces at each foot link 162. Since only a user'sback and feet are rigidly attached to enhancer 110, enhancer 110 may becontrolled by measuring only the ground forces at foot link 162, ratherthan each individual joint.

The algorithm running on controller 1904 (FIG. 19) may also incorporateroutines to save energy and to protect the user and enhancer 110. Forexample, power conservation may be achieved by allowing passive forcesto actuate the one or more jointed links during some phases of motion(e.g., the swing phase). Safety features may include virtual limits onmotion that passively warn a user before the user exceeds the margins ofsafety in operating the device. For example, enhancer 110 may increasethe impedance (resistance to motion) when the user approaches a motionthat exceeds some safe boundary.

Enhancer 110 may also include an interface for external input or output(e.g., by telemetry or by attaching a cable). Such an interface mayallow diagnostic testing, reprogramming, debugging, and the like. Remotemonitoring may also be included.

In summary, enhancer 110 described herein may be used to assist a userin carrying loads. Enhancer 110 may achieve many advantages not realizedwith other devices intended to aid users in carrying loads. Inparticular, enhancer 110 described herein allows a user to move whilecarrying a heavy load, substantially unencumbered by enhancer 110, evenin the un-powered state.

Although the above examples have described various exemplary embodimentsof enhancer 110 using primarily hydraulic actuators, enhancer 110described herein may be actuated by any actuator acting on any number ofjoints. It will be appreciated by persons skilled in the art thatnumerous variations and/or modifications may be made to the describeddevice as specifically shown here without departing from the spirit orscope of that broader disclosure. The various examples are, therefore,to be considered in all respects as illustrative and not restrictive.

1. A lower extremity enhancer to be worn by a user, the enhancercomprising: two leg supports, each having a shank link and thigh link; aback frame connected to proximal ends of the leg supports; two footlinks connected to distal ends of the leg supports; and a plurality ofmechanical actuators configured to apply torques to the leg supports,wherein each foot link is rotatably jointed to a shank link of each legsupport by a spring joint and configured to move in abduction andadduction.
 2. The lower extremity enhancer of claim 1 wherein the springcomprises a compliant plate.
 3. The lower extremity enhancer of claim 1wherein the leg supports may be separable from the back frame.
 4. Thelower extremity enhancer of claim 1 wherein the shank links and thighlinks incorporate adjustment mechanisms to shorten or extend theirlengths.
 5. A lower extremity enhancer to be worn by a user to, theenhancer comprising: leg supports, each leg support having a shank linkand thigh link; a back frame connected to proximal ends of the legsupports; two foot links connected to distal ends of the leg supports;and a plurality of mechanical actuators configured to apply torques tothe leg supports, wherein the lower extremity enhancer is configured tooperate in both an unpowered and powered state.
 6. The lower extremityenhancer of claim 5 wherein when the lower extremity enhancer operatesis an unpowered state, it allows the user to move while carrying a heavyload substantially unencumbered by the enhancer.
 7. A lower extremityenhancer to be worn by a user, the enhancer comprising: two leg supportshaving a plurality of jointed links; a back frame connected to proximalends of the leg supports; two foot links connected to distal ends of theleg supports; a plurality of mechanical actuators configured to applytorques to the leg supports; and a controller, wherein the controllercontrols the mechanical actuators so that the user cannot unknowinglystep too far beyond the center of the gravity of the enhancer and theload.
 8. The lower extremity enhancer of claim 7 wherein the controllerincreases the impedance of the lower extremity enhancer when the userapproaches a motion that exceeds some safe boundary.
 9. A lowerextremity enhancer to be worn by a user, the enhancer comprising: twoleg supports having a plurality of jointed links; a back frame connectedto proximal ends of the leg supports; two foot links connected to distalends of the leg supports; a plurality of mechanical actuators configuredto apply torques to the leg supports; and a controller to control themechanical actuators, wherein the controller controls the mechanicalactuators by estimating the appropriate forces to be applied at a regionor point of the lower extremity enhancer in order to allow the user towalk relatively unencumbered while carrying a load.
 10. The lowerextremity enhancer of claim 9 wherein the controller processes jointvariables, including joint angle and joint velocity, to calculate theappropriate forces to be applied by the mechanical actuators so the useris not encumbered by the enhancer's impedance.
 11. The lower extremityenhancer of claim 9 wherein the controller processes joint variables,including joint angle and joint velocity, to calculate the appropriateforces to be applied by the mechanical actuators to reduce impedance ofthe lower extremity enhancer.
 12. The lower extremity enhancer of claim9 wherein the controller processes the forces applied by the ground onthe foot links to calculate the appropriate forces to be applied by themechanical actuators to reduce impedance of the lower extremityenhancer.
 13. The lower extremity enhancer of claim 9 wherein thecontroller processes the forces applied by the user's feet on the footlinks to calculate the appropriate forces to be applied by themechanical actuators to reduce impedance of the lower extremityenhancer.
 14. The lower extremity enhancer of claim 9 wherein theactuators cause the enhancer to track the motion of the user's lowerextremities.
 15. The lower extremity enhancer of claim 9 wherein thecontroller increases impedance of the lower extremity enhancer when theuser approaches a motion that exceeds a safe boundary.
 16. The lowerextremity enhancer of claim 9 wherein the controller uses the positionof the user's leg to determine the motion of the lower extremityenhancer.
 17. The lower extremity enhancer of claim 9 wherein the one ormore joints of the leg support are actuated passively during swingphase.
 18. The lower extremity enhancer of claim 9 wherein thecontroller includes an interface for remote monitoring.
 19. The lowerextremity enhancer of claim 9 wherein the controller regulates thetorque applied by the mechanical actuators.
 20. The lower extremityenhancer of claim 9 wherein the back frame further includes aforce/torque sensor and the controller processes the measured forces tocalculate the appropriate forces to be applied by the mechanicalactuators to reduce impedance of the lower extremity enhancer.